1. Field of the Invention
The present invention relates to retainer devices for electronic packages, and particularly to a retainer device which exerts no pressure on an electronic package once a heat sink has been attached to the electronic package.
2. Prior Art
A conventional land grid array (LGA) socket often comprises a retainer device to press a central processing unit (CPU) against the socket in advance. A heat sink is then attached to the CPU by a clamp. Referring to FIG. 6, a conventional retainer device 80 for an LGA socket 86 comprises a rectangular base 81, a crank 82 pivotably attached to one side of the base 81, and a clip 83 pivotably attached to an opposite side of the base 81. The socket 86 is surrounded by the base 81. A CPU 87 is placed on the socket 86. When the clip 83 is rotated downwardly, a distal hook 85 thereof enters a space under an offset pressing lever of the crank 82. The crank 82 is then rotated toward the CPU 87 until the pressing lever of the crank 82 engagingly presses the hook 85. A pair of curve pressing portions 84 is formed at opposite sides of the clip 83, for resiliently pressing the CPU 87.
When a heat sink is attached onto the CPU 87, it depresses the CPU 87 slightly. The pressing portions 84 continue to resiliently exert pressure on the CPU 87. That is, the CPU 87 is subjected to pressure exerted by both the heat sink and the pressing portions 84. The combined pressure is liable to damage the CPU and/or solder balls of the socket that contact an underside of the CPU.
Thus, a retainer device for a socket that can solve the above-mentioned problems is desired.
Accordingly, an object of the present invention is to provide a retainer device which can press an electronic package such as a CPU onto a socket, and which can exert no pressure on the electronic package once a heat sink has been attached to the electronic package.
Another object of the present invention is to provide a retainer device which has simple structure.
To achieve the above-mentioned objects, a retainer device in accordance with a preferred embodiment of the present invention is for securing a CPU to a socket. The retainer device comprises a base, a clip pivotably attached to a rear of the base, and a crank pivotably attached to a front of the base. The clip has a frame, and a pair of supporting flanges and a pair of pressing tabs depending from the frame. A hook depends from a front of the clip. The crank has an offset pressing lever and an operation rod. When the operation rod is rotated down toward the socket, the pressing lever drives the hook downwardly. The supporting flanges abut against the base, and the pressing tabs press the CPU. When a heat sink is attached to the CPU, it slightly depresses the CPU. The supporting flanges maintain the pressing tabs at a same level, and therefore the CPU moves downwardly away from contact with the pressing tabs. No pressure is exerted on the CPU by the pressing tabs.
Other objects, advantages and novel features of the present invention will be drawn from the following detailed description of the preferred embodiment of the present invention with the attached drawings, in which: